Re: Reference a counter

Early, Mary wrote:
> Is there any way to provide a reference to a counter value. For example, we
> typically use a superscripted number to reference a table note at the bottom
> of the table. How can we grab the counter value of the table note and place
> it in the cell as a cross reference.

The word 'counter' in your message sets off FAQ alarms. Until XSLT/XPath 2.0
becomes commonplace, counters are best left to procedural languages, not
functional, declarative languages like XSLT. In XSLT, problems involving
incrementing an arbitrary value or computing subtotals tend to have similar
solutions. They generally involve some creative thinking as to how you can
calculate the counter or subtotal you need, without resorting to using a
counter variable at all.

In your case, footnotes very similar to generating a table of contents, and
these tasks involve the same kind of approach as the counter/subtotal problem.
You should set up your stylesheet such that it makes two passes through the
parts of your source document that generate the references. You can do this
with modes. You can also use different methods to calculate the
footnote/reference numbers when the time comes to generate them.

Given XML:
<?xml version="1.0" encoding="utf-8"?>
<data>
  <record>
    <name>Jane Doe</name>
    <note>Likes to play guitar</note>
  </record>
  <record>
    <name>John Public</name>
    <note/> <!-- empty note -->
  </record>
  <record>
    <name>Charlie Brown</name>
    <note>Plays football</note>
  </record>
</data>

...and wanting to produce this output:

  1. Jane Doe [1]
  2. John Public
  3. Charlie Brown [2]
 --------------------------------------
 [1] Likes to play guitar
 [2] Plays football

...your stylesheet would be:


<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="text"/>

  <xsl:template match="/">
    <xsl:apply-templates select="data/record"/>
    <xsl:text> --------------------------------------&#10;</xsl:text>
    <xsl:apply-templates select="data/record/note[normalize-space()]" mode="footnotes"/>
  </xsl:template>

  <xsl:template match="record">
    <xsl:value-of select="concat(' ',position(),'. ',name)"/>
    <xsl:apply-templates select="note[normalize-space()]"/>
    <xsl:text>&#10;</xsl:text>
  </xsl:template>

  <xsl:template match="note">
    <!-- at this point, the current node list only has one note in it,
         so we have to look back up the source tree to find out what
         number it should be -->
    <xsl:value-of select="concat('[',count(preceding::note[normalize-space()])+1,']')"/>
  </xsl:template>

  <xsl:template match="note" mode="footnotes">
    <!-- at this point, the current node list contains the non-empty notes,
         so we can simply use position() to determine the current note's
         number -->
    <xsl:value-of select="concat('[',position(),'] ',.,'&#10;')"/>
  </xsl:template>

</xsl:stylesheet>


This, of course, is just one of several ways to go about it. It should give
you an idea of how careful selection of nodes to process, use of the position
function, and examining the source tree can all help you get away from the 
notion that you need a counter.

   - Mike
____________________________________________________________________________
  mike j. brown                   |  xml/xslt: http://skew.org/xml/
  denver/boulder, colorado, usa   |  resume: http://skew.org/~mike/resume/

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